It is well known with respect to the aforesaid dispensers, that the roll of web material tends to collapse towards its center axis, particularly when a considerable proportion of the web material of the roll has already been dispensed from the center of the roll, whereby the dispensing process is interfered.
To counteract collapsing, WO 98/25848 A1 suggests to statically compress the roll between the opposite end walls of the dispenser to a degree sufficient to prevent collapsing.
Further, WO 2000/011998 A1 suggests to stiffen at least a region of the web material at at least one end of the roll by adding moisture and allowing the moisture to dry, whereby the separate sheets of the web material adhere to each other at said end in order to prevent collapsing.
EP 0 107 487 A1 and U.S. Pat. No. 5,215,211 A both suggest a protrusion depending from an upper end wall of the dispenser and insert into the void at the center of the roll.
Even though the above solutions provide satisfying results, statically compressing the roll to a certain degree requires the user to correctly refill and assemble the dispenser. At the same time, the distance between the opposite end walls of the dispenser need to remain exactly the same over the entire lifetime of a dispenser which will require a certain rigidity and durability. This, however, may increase the manufacturing costs.
Treating the roll itself leads to an additional step of manufacturing of the paper roll.
Furthermore, the stabilizing devices with protrusions inserted into the void at the center of the roll have shown good results at the beginning of depletion of the web material from the roll but do not show satisfactory results once a rather high proportion of the roll has already been dispensed from the center of the roll.